Aerosol emission in a road tunnel

Continuous measurements of aerosol emissions were performed within the scope of emission measurements in the Gubrist tunnel a 3250 m long freeway,tunnel near Zurich, Switzerland, from 20 September to 26 September 1993. The particles in the respirable size range (d < 3 mu m) were found to be mainly tail pipe emissions with very small amount of tire wear and road dust. The calculated PM(3) emission factor for diesel engines was about 310 mg km(-1), where the main part (63%) of the diesel vehicles were heavy-duty vehicles. Thirty-one percent of the PM(3) emissions from diesel Vehicles were black carbon and 0.86% particle bound PAH. Due to the high fraction emitted by diesel engines the contribution of gasoline engines could not be evaluated by the statistical model. During, their residence time in the tunnel the particles undergo significant changes, resulting in a more compact structure. It is concluded that this is mainly due to adsorption of Volatile material from the gas phase to the particle surface. Copyright (C) 1996 Elsevier Science Ltd